noun (n)

• a polyvalent metallic element that resembles chromium and tungsten in its properties; used to strengthen and harden steel(noun.substance)

  Synonym:
  atomic number 42, mo
  

  source: wordnet30
• A rare element of the chromium group, occurring in nature in the minerals molybdenite and wulfenite, and when reduced obtained as a hard, silver-white, difficulty fusible metal. Symbol Mo. Atomic weight 95.9.(noun)

  source: webster1913